Fix compile time warnings building the binutils with a gcc6 compiler.

Fix compile time warnings building the binutils with a gcc6 compiler.

include	* opcode/metag.h (metag_scondtab): Mark as possibly unused.
	* opcode/nds32.h (nds32_r45map): Likewise.
	(nds32_r54map): Likewise.
	* opcode/visium.h (gen_reg_table): Likewise.
	(fp_reg_table, cc_table, opcode_table): Likewise.

bfd	* oasys.c (oasys_archive_p): Fix indentation.
	* elf32-nds32.c (nds32_elf_relax_section): Use an unsigned
	constant for left shifting.